A painting that was stuck in a warehouse for 150 years is revealed to be worth over $3 million

A version of Jacob Jordaens' Mileager and Atalanta, on view at Madrid's Museo del Prado. Wikipedia Commons

A painting by 17th century Flemish master painter Jacob Jordaens, titled Meleager and Atalanta, has been discovered in the storeroom of the Swansea Museum in Wales.

The work, which is thought to have been owned by the museum for roughly 150 years and is now valued at £3 million ($3,878,745), was always thought to be a copy, and it thus remained in storage, away from the eyes of museum-goers. No longer will this be the case, as the museum plans to unveil the painting next month.

The painting's true identity was discovered by art historian and presenter of BBC1's Fake or Fortune, Bendor Grosvenor, after he was combing through the website Art UK, and was skeptical when the work's creator was listed as unknown.

"I'm bit of a nerd when it comes to looking through websites and catalogues," he told the Sunday Times. "I saw this one and had strong suspicions."

According to the Independent, a label on the back of the painting said it was an 18th century copy. However, the frame—which was analyzed at London's Courtauld Institute—was dated by experts to between 1619 and 1622.

Meleager and Atalanta was then further authenticated by Ben van Beneden, the director of Antwerp's Rubenshuis museum, who described the discovery as "a great and astonishing find."

Though once deemed a copy, the painting is now believed to have been the preliminary canvas for another Jordaens work that sits in Madrid's Museo del Prado: "It is Jordaens trying out his ideas before he did the one which is now in Madrid," Grosvenor told the Sunday Times.